With the advent of suction robots such as window cleaning robot, window cleaning work becomes more easy and simple. Nowadays, the window cleaning robots available in the market mostly allow the robots to be adsorbed on windows in a vacuum adsorption manner. In order to prevent the robots from falling, the adsorption force on the windows is relatively large. Thus, in order to take off the robots from the windows, it takes a relatively long time to release air from the suction cup. In the existing robots, the vacuuming apparatus is still in operation at the time of air release. Accordingly, the air release speed of the suction cup is impaired, and also waste of energy occurs.